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Project Dates

May 20, 2000 to May 22, 2000

Project Description

On 21 May 2000, several isolated severe thunderstorms broke out in northwest Missouri. They produced golfball sized hail, up to 70 MPH wind gusts and spawned a F1 tornado. Forecasts for this region were for sunny skies through the afternoon as the conditions supporting convective development were subtle and difficult to recognize. This challenging forecasting scenario provides a good teaching case for identifying triggers of severe thunderstorms.

Objectives

This case provides an example of severe weather in the wake of a cold frontal passage, in northwest flow aloft.

Data Access for COMET Case Study 033

Project Dates

August 11, 2000 to August 13, 2000

Project Description

On 12 August 2000, flooding rains hit the state of New Jersey. The rains were associated with regenerative warm-topped convection, and in many areas, including the hardest hit Sparta, roads were closed, bridges washed out, mudslides occurred and motorists were stranded. Terrain-locked convection over Sparta resulted in over 9 inches of rain in 8 hours, with media reports of as much as 14 inches. Rainfall rates were as high as 4 inches per hour.

Objectives

This case provides an example of terrain-locked convection.

Data Access for COMET Case Study 034

Project Dates

November 19, 2000 to November 21, 2000

Project Description

On 20 November 2000, Buffalo, NY was hit with a lake effect snowstorm with strength unseen in several years, and a disruptive force unequalled in nearly 25 years.Buffalo received 2 feet of snow in a relatively short time, with most falling in a 7-hour period. Frequent lightning occurred all afternoon with this snowfall, and the timing could not have been worse, as the brunt of the snowfall began around 2 p.m. local time. Many people spent the night in autos, and buses full of school children were trapped, eventually spending the night in stores or makeshift shelters.

Objectives

This case allows the study of a classic severe lake effect snowstorm.

Data Access for COMET Case Study 032

Project Dates

February 15, 2001 to February 17, 2001

Project Description

On Friday, February 16, 2001, a major snowstorm hit the Seattle area as an arctic front moved from Canada into Washington, interacting with warmer moist, Pacific air. Accumulations generally ranged from four to eight inches of snow across most of the lowlands of western Washington with a foot of snow over the hills around Seattle.

Objectives

This case provides an example of an arctic front moving through the complex terrain of the West.

Data Access for COMET Case Study 036

Project Dates

June 5, 2001 to June 19, 2001

Project Description

Allison spent 5 days over Southeast and East Texas and dumped record amounts of rainfall across the area. Nearly 37 inches of rain was recorded at the Port of Houston during this time. Damage estimates in Harris County alone (includes the Houston Metro area) surpassed $4.88 billion. Allison will likely go down as the costliest tropical storm to ever effect the United States. On the morning of June 11, 2001, Tropical Storm Allison was moving into the marshes/bayous of southeast Louisiana. The maximum amounts of rainfall occurred in the Vermilion and Atchafalaya basins of south central Louisiana that saw heavy rains each day from the 5th through the 11th. The highest amount reported from Louisiana was 27.55 inches at salt point in St. Mary parish. On the 11th, the low that was once Tropical Storm Allison developed over land, which had never happened before. This was mainly due to a jet streak riding along the subtropical jet to its north and northeast enhancing its outflow, which in turn led to a stronger surface low. As it edged farther inland that afternoon, it finally weakened and lost the eye.Allison tracked out of Mississippi into southern Alabama on the afternoon on the 11th. Severe weather broke out in Georgia, South Carolina, and southern North Carolina on the 13th and 14th. As the system slowed in North Carolina,flooding became a major problem. As the remnants of Tropical Storm Allisonmoved north-northwest along the eastern edge of the DelmarvaPeninsula, a cold front moved in from the west. This allowed moisture from Allison to pool along the front. Southeast Pennsylvania saw torrents of rain during the afternoon and evening of June 16th. Ultimately, Willow Grove Naval Air Station received 10.16 inched while Chanfont recorded 10.17 inched for the 24-hour period ending the morning of the 17th. One June 18th, the last of the rain associated with Allison left eastern Maine during the early morning. The project objective is to allow in depth investigation of abnormal tropical storm behavior.

Data Access on COMET Case Study 037

Project Dates

January 28, 2002 to January 30, 2002

Project Description

On the 28th, an Arctic Front surged south across Kansas, leaving a shallow layer of sub-freezing air in its wake. Meanwhile, an 850mb low was positioned over New Mexico. As the 850mb low moved east across New Mexico on the 29th and 30th, much warmer, moisture-laden air was transported north across the southern plains in a layer approximately 3,000 feet thick, trapping the sub-freezing layer beneath. On the evening of the 30th, the 850mb low crossed the New Mexico/Texas border. A mid-upper level trough moving east across the southern Rockies provided sufficient lift across the region. Widespread freezing rain and sleet developed late in the afternoon of the 29th across south-central Kansas and continued through the night of the 30th, eventually changing to snow early on the morning of the 31th.

Objectives

This case expands our severe weather coverage to Kansas and allows an in-depth study of dynamics producing the these conditions.

Data Access for COMET Case Study 042

Project Dates

June 10, 2002 to June 14, 2002

Project Description

The 137,760-acre Hayman Fire generated massive amounts of heat, dust and moisture into the sky southwest of Denver. The towering smoke plume from this fire spawned nighttime thunderstorms across the Great Plains. On the night of Monday, June 10th, southwesterly winds drove the smoke and the clouds into northeastern Colorado, where showers and golf ball-sized hail were reported in Washington County near Akron. The next night, Tuesday, June 11th, west winds pushed the clouds east into Kansas, where violent weather erupted and two small tornadoes were triggered in south- central Kansas.

Objectives

This case allows an in-depth study of dynamics of fire weather, such as the impact of fire heat, dust and moisture on the precipitation, and the enhancement of hail and tornado formation.

Data Access for COMET Case Study 043

Project Dates

November 10, 2002 to November 11, 2002

Project Description

A major outbreak of severe weather and tornado occurre across the Tennessee and Ohio valley regions on the 10th -11th of November 2002. This resulted in damage to 13 states from the Gulf Coast to western Pennsylvania. A total of 75 tornados touched down on the 10th, resulting in at least 36 deaths. A tornado rated as an F-4 on the Fujita Scale, struck Van Wert county in Ohio. In Tennessee, the community of Mossy Grove was nearly destroyed by a mile-wide tornado that claimed 12 lives. This is the worst tornado outbreak in November in a decade, caused by an unseasonably strong upper troposheric jet stream. This resulted in cold air surging down from Canada, and the subsequent lifting of warm moist air from the Culf of Mexico adding extra energy to the system. This triggered a thousand mile front stretching from the Gulf Coast to Pennsylvania.

Objectives

This case allows an in-depth study of dynamics of tornado formation in the Fall season.

Data Access for COMET Case Study 044

All photos courtesy of NCAR. Please click on image for full resolution.